Some pupils took a Math mock exam. Their average score was 75.1 marks. One of the pupils' scores was wrongly recorded as 78 marks instead of 87 marks. As a result, the average score was calculated as 74.6 marks. How many pupils sat for the mock exam?
| |
If that pupil's score was 87 |
If that pupil's score was 78 |
| Number of pupils |
1 u |
1 u |
| Average score |
75.1 |
74.6 |
| Total score |
75.1 u |
74.6 u |
Difference in the scores due to being wrongly recorded
= 87 - 78
= 9
Difference in total scores of the pupils is due to the difference in the wrongly recorded score.
75.1 u - 74.6 u = 9
0.5 u = 9
1 u = 9 ÷ 0.5 = 18
Number of pupils = 18
Answer(s): 18
